Django access data passed to form

Hey,

I have got a choiceField in my form, where I display filtered data. Tofilter the data I need two arguments. The first one is not a problem,because I can take it directly from an object, but the second one isdynamically generated. Here is some code:

I would like to change the parent_id that is passed into theObjtree.objects.filter. As you can see I tried in the init function,as well with kwargs and then calling it withself, but that doesnt work, since its out of scope... it was prettymuch my last effort. I need to acccess it either trough the initialparameter or directly trough parent_id field, since it already holdsits value (passed trough initial).